2.  Mutations are a result in a change in DNA sequence › A protein with a different AA sequence could be produced. › Germ Cell - If mutations occur in sex cells they may be passed on to the next generation. › Somatic- A mutation occurring only in body cells may be a problem for the individual but will not be passed on to the offspring.  Mutations may be classified as chromosomal alterations or gene mutations › Chromosomal alterations are generally more severe because many genes are usually involved.

3. Significance of Mutations Most are neutral Eye color Birth marks Some are harmful Cystic Fibrosis Down Syndrome Some are beneficial Sickle Cell Anemia to Malaria Immunity to HIV

4. What Causes Mutations? There are two ways in which DNA can become mutated: – Mutations can be inherited. Parent to child – Mutations can be acquired. Environmental damage Mistakes when DNA is copied

5.  Silent mutation › any mutation that is not expressed because it does not cause a change in amino acid chain.  Point mutation › base-pair substitution › 1 base is replaced by a different base

6. Point mutation Only one nucleotide changes, but it makes a different protein

7. Gene Mutations Point Mutations – changes in one or a few nucleotides – Substitution THE FAT CAT ATE THE RAT THE FAT HAT ATE THE RAT – Insertion THE FAT CAT ATE THE RAT THE FAT CAT XLW ATE THE RAT – Deletion THE FAT CAT ATE THE RAT THE FAT ATE THE RAT

8. Frameshift Causes every codon in the DNA sequence to be changed after the mutation: Insertion- one or more bases are added Deletion- one or more bases are removed A

9.  Deletion - part of chromosome is left out.  Duplication - part of chromatid breaks off add attaches to the sister chromatid creating a duplication of genes on the same chromosome. › Deletion and duplication mutations are errors that occur during crossing over in Meiosis I.  Translocation - when part of one chromosome breaks off and is added to a different chromosome.  Inversion - when part of a chromosome breaks off and is reinserted backwards.

11. Chromosome Mutations Changes in number and structure of entire chromosomes Original Chromosome ABC * DEF DeletionAC * DEF DuplicationABBC * DEF TranspositionACB * DEF InversionAED * CBF TranslocationABC * JKL GHI * DEF

12. A dinky Y chromosome and the hairy ear gene on the Y chromosome Chromosomal Deletion